A fuel cell is an electrical device which converts the energy potential of fuel to electricity through an electrochemical reaction. In general, a fuel cell comprises a pair of electrodes separated by an electrolyte. The electrolyte only allows the passage of certain types of ions. The selective passage of ions across the electrolyte results in a potential being generated between the two electrodes. This potential can be harnessed to do useful work, such as powering a motor vehicle or home electronics. This direct conversion process increases the efficiency of power generation by removing mechanical steps required by traditional power generating device, such as turbine plants. Additionally, the combination of higher efficiency and electrochemical processes results in an environment-friendly product.
A solid oxide fuel cell (“SOFC”) is a device that is approximately 40% efficient in converting the energy potential of fuel to electricity through an electrochemical reaction. SOFC possesses three basic parts: an anode that produces electrons, a cathode that consumes electrons, and an electrolyte that conducts ions but prevents electrons from passing. Unlike many fuel cells, the SOFC is capable of running on multiple types of fuel (e.g., hydrogen, propane, and diesel) without a separate chemical reformer. Therefore, the SOFC system generates a larger amount of electricity per pound that competitive fuel cell systems, such as systems incorporating proton exchange membrane fuel cells.
There are two general structural types of SOFC, tubular cells and planar cells, in referring to the shape of their respective fuel cells which are shaped cylinders as or plates. Solid oxide fuel cells operate at relatively high temperatures, around 850-1000 degrees Centigrade. As a result of these high operating temperatures, the planar cells suffer from difficulties with sealing around the ceramic parts of the cell. Thus, there exists a need for an improved fuel cell system that generates low internal thermal stresses and accordingly has reduced sealing requirements.